The human nose is a relatively complex structure that allows for the inhalation of air and exhalation of air and carbon dioxide and other cellular waste products. The nose also accomplishes physiological functions including humidification, temperature control and filtration of the inspired air. The nose additionally is a sensory organ responsible for the olfactory sense. For most people, the nose performs these functions efficiently and relatively trouble-free. However, patients often complain of symptoms relating to restricted airflow in their nasal passages. The septal cartilage structure of the nose divides the nose into two passages. These passages are typically described or referred to as nostrils. Inspired air moves through the nostrils, the nasal vault, and the nasopharyngeal wall, the pharynx, larynx, trachea, bronchi and reaches the alveoli in lungs. Inhalation and exhalation are responsive to movement of the diaphragm and the intercostal muscles of the ribs. It is estimated that more than 50% of the total respiratory resistance of the respiratory tract occurs in the nose. It is known that airway obstruction may be attributable to various factors, including deviated septum, suboptimal position and rigidity of the lateral nasal walls, etc. The internal nasal valve is described as the space between the fold of the upper lateral cartilage (ULC) and the nasal septum. The angle between the septum and the upper lateral cartilage normally ranges between 10 and 15 degrees. It is generally accepted that nasal resistance behaves in accordance with Poiseuille's law and Bernoulli's principle, which means that small changes in the nasal valve area have an exponential effect on the airflow. Patients with less than a 10 degree angle at the internal nasal valve usually have airflow obstruction and are diagnosed with internal valve stenosis. The internal nasal valve may also be narrowed due to thickening of the septum or by a deviated septum. Additional causes of nasal obstruction include trauma to the nose, face or head, burns, and elective surgery. Surgery of the nose involves repositioning of the nose's bony and cartilaginous structures. Excessive scarring due to aggressive resection may also lead to resultant narrowing of the nasal valve area. The internal valve may also become collapsed due to poor cartilage quality or position. As the internal valve collapses, the airflow becomes obstructed. The external nasal valve is composed of the nasal ala and supporting structures of the lower lateral cartilages.
These areas are named valves because they regulate the cross-sectional area of the nasal airway and perform dynamic functions. The collapse of the lateral nasal walls at the internal valve is known to be associated with a reduction rhinoplasty procedure commonly referred to as ‘hump removal’. During such reduction rhinoplasty, a hump in the cartilaginous and/or bony dorsum of the nose needs to be resected, which leads to reduction of the overall valve area and destabilizing of the ULC. The patient may experience post-surgical breathing problems if the nasal valve is not properly repaired after this procedure. This nasal valve reconstruction is typically done by the surgeon emplacing unilateral or bi-lateral spreader grafts on the nasal septum from the cephalic to the caudal portion of the nasal septum. Such devices and procedures widen the cross-sectional area of the upper nasal valve. However, there are deficiencies present in and associated with the use of conventional spreader grafts, which are typically made from autologous cartilage. The deficiencies include the need for autologous cartilage harvesting resulting in donor site morbidity, and increased pain and duration of the procedure. Although non-absorbable spreader graft implants exist, surgeons prefer not to use them due to the increase risk of complications such as infection and extrusion.
Therefore, there is a need in this art for novel bioabsorbable, multilayer spreader grafts for nasal reconstruction procedures that increase the spacing between nasal upper lateral cartilages without using permanent foreign body material to achieve permanent repositioning of the upper lateral cartilages and which provide improved structural support in patients undergoing plastic or reconstructive surgical nasal procedures. There is also a need for novel bioabsorbable spreader grafts which promote tissue ingrowth and minimize long term complications, and which are relatively easy for the surgeon to implant, and which further provide a superior result for the patient.